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[en] The objective of this project was the study of the effects of gravity and curvature on the velocity profiles and pressure gradient for three different fluids flowing through a bend. The bend was of 90 having square cross-section (1 cm/sup */ 1cm). The flow at inlet was assumed uniform. The three fluids under analysis were Sodium, Lithium and Water. For this purpose Navier Stoke's equations that model the flow were discretized using power law scheme. A computer code SIMPMHD as transformed to solve the problem. Flow was considered laminar and results that is velocity and pressure gradient profiles obtained were compared with the theoretical. The results obtained differ from the theoretical results due to turbulence, which was not considered in the present study. The pressure drop calculated through the bend was compared with the pressure drop through same length of horizontal pipe. For laminar case the results were found satisfactory. (author)
[en] Medium energy proton induced reactions, including fission, in 238U and 209Bi have been studied. The inelastic interactions of protons with heavy nuclei have been described by a model in which the reaction proceeds in two steps. The first step is the fast cascade where a series of individual particle-particle collision occurs within the nucleus leaving a highly excited cascade residual nucleus assumed to be in thermal equilibrium. In the second step, the excited nucleus disposes of its energy by evaporation of neutrons and light charged particles. The cascade stage is calculated by the Monte Carlo method of computer simulations using the medium energy cascade calculation program MECC-7 originally developed by Bertini at Oak Ridge National Laboratory. The evaporation phase of the reaction has been calculated by the statistical theory of evaporation. The fission cross sections, the cross sections for the spallation residues, and the number of nucleons lost by the target before and after fission are calculated and compared with experiment for 155 MeV and 1 GeV protons incident on 238U and 209Bi
[en] This thesis is concerned with the magnet properties of magnetostrictive FeSiBC amorphous films based on the METGLAS 2605SC composition; the films have been produced by RF magnetron sputtering. The ribbon form of the material has excellent magnetic properties, which are ideal for magnetic thin film sensors. The deposition of films is a complex process which is strongly dependent upon many parameters; these are discussed and investigated in detail in this thesis. It has been demonstrated that it is possible to produce FeSiBC films with magnetic properties comparable to those of the original METGLAS 2605SC ribbon material used as the sputtering target. The magnetic properties were principally investigated using the magneto-optical Kerr effect, with both point hysteresis measurements and domain imaging. These measurements were made using equipment which was constructed during the course of this present work. A significant, reproducible in-plane radial anisotropy was observed in the as-deposited films, which was attributed to the residual field produced by the magnetron sputter source. The effects of various treatments on the samples were investigated, including the use of forming fields, stress and thermal processing. The deliberate introduction of stress into these materials is found to allow excellent control of both the direction and magnitude of the magnetic anisotropy. A high degree of control is demonstrated in tailoring the anisotropy field, using the technique of stress annealing. The treatments are evaluated for their potential to enable the magnetic anisotropy in magnetostrictive device applications to be controlled. A simple new technique is described for the measurement of saturation magnetostriction in thin films deposited onto rigid substrates. The method is based on mechanically introducing a small curvature into the substrate. The strain induced anisotropy is measured using the magneto-optical Kerr effect. Quantification of the film strain is obtained using optical interference and stylus measurements; this allows the saturation magnetostriction to be determined. No information about the mechanical properties of the substrate is required and, providing that the Young's modulus of the film is known accurately, the values of magnetostriction obtained are accurate and absolute. It is envisaged that the technique could be applied to a wide variety of films deposited onto commercially important substrates. The possibility of using magnetostrictive FeSiBC films as Magneto Impedance sensors has also been investigated. (author)
[en] We investigate the supersymmetric extension of the hot NUT-Kerr-Newman-Kasuya spacetime. Along with four standard supersymmetries, this type of spacetime admits fermionic symmetries generated by the square root of bosonic constants of motion except the Hamiltonian. Such new supersymmetries correspond to the Killing-Yano tensors, which play an important role in solving the Dirac equation in curved spacetime
[en] We study pseudo-classical spinning particles in the spacetime of the Reissner-Nordstrom black hole. We derive the constants and the equations of motion and investigate bound state orbits in a plane
[en] The different excitation methods of X-ray spectral analysis with proton induced X-ray emission (PIXE) and radioisotope (109Cd) induced X-ray fluorescence (RIXRF) are evaluated and compared with regard to sensitivity, detection limit, precision, accuracy and cost, using NIST orchard leaves and pine needles standard reference materials. The accuracy and precision of both the methods for biological analysis using appropriate standards are shown to be better than 5%. The comparison of sensitivity results indicates that PIXE is comparatively more sensitive for light elements (K to Zn) and RIXRF for heavier elements (Z>33), the crossing points being at Z=33. Based on the present findings, PIXE is recommended for the analysis of bio-environmental samples containing low level biologically important trace elements in the range of Z=19-30. PIXE techniques have been applied here to the analysis of 10-15 elements in some biological samples and standards with good accuracy and precision without prior pre-concentration except oven or freeze drying; a combination of PIXE and RIXRF represents a complete investigation tool for the analysis of 15-20 light and heavy elements
[en] The kinetics of initial stage sintering of UO2 powder was reinvestigated, using Ar-10 % H2 atmosphere. The effect of the addition of neodymium oxide was studied. The results revealed that grain boundary diffusion mechanisms predominate. The values of activation energies were found to be 48.48+-3.51 Kcal/mole in the temperature range 870 - 9420C and 89.88+-9.87 Kcal/mole in the temperature range of 942 - 10300C for UO2, and 115.61+-7.77 Kcal/mole in the temperature range 1030 - 11500C for UO2+Nd2O3. A remarkable decrease in the calculated diffusion coefficient occurs by the addition o
[en] Walls of Interlocking Stabilised Soil Blocks (ISSBs) have been considered in low-cost houses around the world especially in developing countries. These were reported to be very weak in resisting the lateral load (e.g. wind or earthquake) without special considerations. In this paper, mechanical properties (compressive strength, elastic modulus, pre/post crack energy absorbed and toughness index) of ISSBs with three configurations and seven combinations of plain and fibrous mortar cubes are experimentally evaluated. Sisal fibre and rice straw (2% and 5%, by cement mass) were considered for fibrous mortar. Empirical equations were developed to predict elastic modulus. It was found that ISSBs had reasonable strength to be considered for masonry. The failure load and toughness index of 2% sisal fibre samples was improved by 10% and 16%, respectively, whereas 2.21 times enhancement was found in elastic modulus. Thus, 2% sisal fibre in plaster (i.e. reinforced coating) would likely improve the lateral resistance of interlocked masonry walling.
[es]Los muros de bloques de suelo estabilizados entrelazados (ISSB) se han utilizado en casas de bajo costo en todo el mundo, especialmente en países en desarrollo. Es conocido que estos muros presentaban debilidad frente a cargas laterales (por ejemplo, viento o terremoto) sin consideraciones especiales. En este trabajo se han evaluado las propiedades mecánicas (resistencia a compresión, módulo elástico, absorción de energía pre/post agrietamiento e índice de tenacidad) de ISSB con tres configuraciones y siete combinaciones de cubos de morteros liso y fibrosos. Para los morteros fibrosos se utilizó fibra de sisal y paja de arroz en proporciones del 2% y 5% con respecto a la masa de cemento. Se desarrollaron ecuaciones empíricas para predecir el módulo elástico. Los resultados mostraron que los ISSB poseen una fortaleza suficiente para poder ser utilizados en obras de albañilería. La carga de falla y el índice de tenacidad de las muestras de fibra de sisal al 2% se mejoraron en un 10% y un 16%, respectivamente, mientras que se encontró una mejora de 2.21 veces en el módulo de elasticidad. Por lo tanto, un 2% de fibra de sisal en yeso (es decir, revestimiento reforzado) probablemente mejoraría la resistencia lateral de las paredes.
[en] Atomic Energy Centre, Dhaka under the Bangladesh Atomic Energy Commission was recently awarded a research contract from the International Atomic Energy Agency to investigate the levels of micronutrients (K, Ca, Mn, Fe, Ni, Cu, Zn) and pollutants (As, Pb) in health indices (hair, blood, etc.) to study their interactions and impacts on the nutritional status of Bangladeshi population. The project was scheduled to start in December 2001 and to be completed by November 2002. To date, sampling and sample preparation techniques for heavy metal analysis in hair and blood using XRF/PIXE have been investigated, and some preliminary work on sample analysis has been performed. It indicates that both PIXE and XRF methods can be used for the determination of nutritionally important trace metals in health indices after a simple sample treatment for volume reduction either by oven or freeze drying. Results of Biochemical assessment of nutritional status of Bangladeshi pre-school children under normal and malnutrition conditions from a previous study has been given in the Results section of this paper. There has been found a positive correlation of malnutrition with some nutritional parameters such as fasting blood glucose, serum total protein, serum total albumin, and serum Cu and Zn levels. Hair Zn level had no significant correlation (p>0.05) with serum Zn level but hair Cu level had a positive correlation with serum Cu level. The trace element concentrations in hair of both normal and malnourished children in the age group of 1-5 years, as studied do not show any regular dependence on nutritional status of the subjects. Only the low copper content in the hair of the malnourished group can possibly be linked with nutritional disorders. (author)
[en] Objective: To assess the feasibility and efficacy of a novel, minimally invasive spinal surgery technique for the correction of lumbar spinal stenosis involving unilateral approach for bilateral decompression. Study Design: Cross-sectional observational study. Place and Duration of Study: Neurosurgery Department of PGMI, Lady Reading Hospital, Peshawar, from January to December 2010. Methodology: A total of 60 patients with lumbar stenosis were randomly assigned to undergo either a conventional laminectomy (30 patients, Group A), or a unilateral approach (30 patients, Group B). Clinical outcomes was measured using the scale of Finneson and Cooper. All the data was collected by using a proforma and different parameters were assessed for a minimum follow-up period of three months. Data was analyzed by descriptive statistics using SPSS software version 17. Results: Adequate decompression was achieved in all patients. Compared with patients in the conventional laminectomy group, patients who received the novel procedure (unilateral approach) had a reduced mean duration of hospital stay, a faster recovery rate and majority of the patients (88.33%) had an excellent to fair operative result according to the Finneson and Cooper scale. Five major complications occurred in all patient groups, 2 patients had unintended dural rent and 2 wound dehiscence each and fifth patient had worsening of symptoms. There was no mortality in the series. Conclusion: The ultimate goal of the unilateral approach to treat lumbar spinal stenosis is to achieve adequate decompression of the neural elements. An additional benefit of a minimally invasive approach is adequate preservation of vertebral stability, as it requires only minimal muscle trauma, preservation of supraspinous/intraspinous ligament complex and spinous process, therefore, allows early mobilization. This also shortens the hospital stay, reduces postoperative back pain, and leads to satisfactory outcome. (author)